<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>vw和vh</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        div{
            width: 100vw;
            height: 100vh;
            background: yellow;
        }
    </style>
</head>
<body>
    <!-- vh与vw -->

    <!-- 
    vh view-height 
    100vh === 视口的高度
    vw view-width
    100vw ==== 视口的宽度

    iphone6 100vw === 375px  1vw = 3.75px
    iphone6 plus 100vw === 414px 1vw=4.14px

    html font-size js代码动态，
    font-size ???vw
    -->
    <div>
        
    </div>
</body>
</html>